EP0040571B1 - Stacking device for stacking articles circulating one after the other along a conveyor - Google Patents

Abstract

1. Stacker for stacking products each formed of a plate (3) supporting an object (5), of the type comprising two frames disposed on each side of a transport path (1, 2) along with the products travel one after the other ; means (27) for immobilizing the products when they are between the frames ; two lifting carriages (8) movable vertically along the frames, these carriages facing each other and each comprising lifting means (13) having a lifting arm (14) adapted to advance under the product immobilized between the frames, the lifting means (13) being hingedly mounted about a horizontal shaft (12) extending parallel to the transport path (1, 2) and being adapted for pivoting between an active position in which they are in abutment against a stop (16) fixed on the corresponding carriage (8) while their lifting arm (14) advances horizontally above the transport path (1, 2) and an inactive position in which they are distant from the stop (16) whereas their lifting arm (14) extends outside the transport path (1, 2) ; and drive means for communicating cyclically to the carriages a rising movement during which their lifting means raise the immobilized product to a height sufficient to allow a new product to arrive and stop between the frames, then a downward movement during which their lifting means deposit the raised product on the new product and then come underneath this latter, characterized in that the pivoting shaft (12) of the lifting means (13) of the same carriage (8) is provided with a radial stud (18) adapted for cooperation with a by-pass cam (19) mounted for pivoting on the corresponding frame, about an axis (20) perpendicular to the pivoting shaft (12) of the lifting means ; and in that the by-pass cam (19) is urged resiliently against a stop (25) provided on said corresponding frame, the stop (25) being disposed so that, during the downward movement of the corresponding carriage (8), the corresponding stud (18) causes the lifting means (13) to move into their inactive position when it meets the by-pass cam (19) which is immobilized against the stop (25), and that during the upward movement of the corresponding carriages (8) the associated stud (18) causes the by-pass cam (19) to pivot about the axis (20) so as to move it away from the stop (25) and to retract it.

Description

The present invention relates to a stacker for stacking products, each consisting of a plate supporting an object, of the type comprising two frames arranged on either side of a transport path along which the products circulate one after the other. others ; means for immobilizing the products when they are between the frames; two lift trucks vertically movable along the frames, these trucks facing each other and each comprising lifting members comprising a lifting wing capable of advancing under the product immobilized between the frames, the lifting members being articulated around a horizontal axis extending parallel to the transport track and being able to pivot between an active position in which they are in abutment against a retainer fixed on the corresponding carriage while their lifting wing advances horizontally above the track transport, and an inactive position in which they are distant from the retainer while their lifting wing extends outside the transport path; and drive means for cyclically communicating to the carriages an upward movement during which their lifting members raise the immobilized product to a height sufficient to allow the arrival and stopping of a new product between the frames, then a movement descending during which their lifting members deposit the lifted product on the new product and then come under it.

The document FR-A-1 494 910 describes a stacker of this type whose lifting members pivot between their active position and their inactive position under the control of rollers moving along tortuous paths defined by straight ramps, cams and retractable shutters.

The solution proposed in this document for controlling the lifting members is however not entirely satisfactory since it results in the production of a complex and expensive stacker.

The present invention proposes to overcome these drawbacks and, to do this, it relates to a stacker of the aforementioned type which is characterized in that the pivot axis of the lifting members of the same carriage is provided with a radial lug capable of cooperating with a bypass cam pivotally mounted on the corresponding frame, around an axis perpendicular to the pivot axis of the lifting members; and in that the bypass cam is elastically biased against a stop provided on said corresponding frame, the stop being arranged so that, during the downward movement of the corresponding carriage, the corresponding lug causes the lifting members to move in their inactive position when it meets the bypass cam which is immobilized against the stop, and that during the upward movement of the corresponding carriage, the associated lug causes the bypass cam to pivot around the axis so as to move it away from the stopper and retract it.

During the downward movement of the carriages, the lifting members can therefore, thanks to the bypass cams, pivot to their inactive position before they meet the plate of the new product. The latter is therefore protected against damage which the bearing wing of the lifting members could cause it by sliding against it.

Furthermore, during the upward movement of the carriages, the lugs are not liable to be damaged by the bypass cams since these are retractable.

According to a preferred embodiment of the invention, the drive means consist of two sets of identical cams and on which the carriages rest, each assembly bearing on a horizontal spacer provided on the corresponding frame and comprising two wedged cams each on a lever forming one of the transverse sides of a deformable parallelogram, and by a jack extending parallel to the transport track, this jack being interposed between a fixed base and a connecting arm connecting the two deformable parallelograms.

Thanks to this set of provisions, the two carriages move in perfect synchronism, which guarantees proper operation of the stacker.

Advantageously, the drive means raise the carriages against the action exerted by tension springs, interposed between them and the lower part of the frames. Such springs therefore facilitate the descent of the carriages to their low position.

The stacker according to the present invention is further characterized in that it comprises means for pushing the stack of products when it reaches a predetermined height, these means bringing the stack downstream of the frames by moving it along the track. transport.

Preferably, the means for pushing the stack comprise at least one cleat which can be moved alternately along the part of the transport path located between the frames, this cleat rising above the plate of the product resting on the transport path. and being capable of being retracted when it moves in the direction in which it does not exert its pushing action.

According to a particular embodiment, the cleat is articulated at one of the ends of a rack running along the transport track and movable parallel to the latter under the action of a motor member engaged with it.

The stacker according to the present invention is further characterized in that the means provided for immobilizing the products between the frames are constituted by stops fixed to the front end of each carriage, these stops being in front of the plate of the product to be immobilized when the carriages are in their high position, and under the transport track when these are in their low position.

According to another characteristic of the stacker according to the present invention, the two frames each comprise two vertical uprights constituted by U-shaped profiles whose wings are parallel to each other and face each other, while the carriages are each constituted by a horizontal beam whose ends carry rollers cooperating with the wings of the vertical uprights of the corresponding frame.

• la figure 1 est une vue de face d'un gerbeur conforme à l'invention dont les chariots sont représentés dans leur position basse ;
• la figure 2 est une vue analogue à la figure 1 mais dans laquelle les chariots sont dans leur position haute ;
• la figure 3 est une vue analogue à la figure 1 mais dans laquelle une pile de produits est en cours de déplacement le long de la voie de transport ;
• la figure 4 est une vue en coupe effectuée selon la ligne IV-IV de la figure 2 ;
• la figure 5 est une vue en perspective d'une came de contournement ;
• les figures 6 à 9 sont des vues de côté partielles et à échelle agrandie, ces vues étant effectuées selon la ligne A-A de la figure 1 et montrant l'un des chariots dans quatre positions différentes ; et
• la figure 10 est une vue partielle effectuée selon la ligne B-B de la figure 9.

An embodiment of the present invention will be described below by way of nonlimiting example with reference to the accompanying drawings in which:

• Figure 1 is a front view of a stacker according to the invention whose carriages are shown in their low position;
• Figure 2 is a view similar to Figure 1 but in which the carriages are in their upper position;
• Figure 3 is a view similar to Figure 1 but in which a stack of products is being moved along the transport path;
• Figure 4 is a sectional view taken along the line IV-IV of Figure 2;
• Figure 5 is a perspective view of a bypass cam;
• Figures 6 to 9 are partial side views and on an enlarged scale, these views being taken along the line AA of Figure 1 and showing one of the carriages in four different positions; and
• FIG. 10 is a partial view taken along line BB of FIG. 9.

The stacker according to the invention is more particularly intended for stacking molded concrete objects resting on a demoulding plate, these objects being able for example to consist of slabs, fence posts, etc. It is used in conjunction with a transport track essentially comprising two parallel beams 1 extending horizontally and carrying rollers 2 on which the products to be stacked circulate one after the other in the direction of the arrow F. In the example shown, the products are made up by a release board 3 provided with feet 4 and by a slab 5 resting on the board. Referring in particular to FIG. 4, it will be noted that the spacing of the feet 4 is greater than that of the side members 1 and that thus the boards 3 can rest on the rollers by means of their lower face.

The stacker comprises first of all two identical frames arranged on either side of the transport track, each frame comprising two vertical uprights 6 connected below their central part by a horizontal spacer 7 and constituted by U-shaped profiles implanted on the ground in such a way that their wings are parallel to each other and turned towards each other.

The stacker also includes two forklifts 8 movable along the frames between a low position visible in Figures 1 and 3 and a high position visible in Figure 2. Each of these trucks is formed by a horizontal beam 9 at the ends of which are fixed two plates 10 each carrying two rollers 11 cooperating with the wings of the corresponding amount 6.

With particular reference to FIG. 4, it will be noted that the longitudinal members 9 are U-shaped profiles, the branches of which face outwards relative to the transport track and that the plates 10 are in the form of trapezoids, the large base is in the plane containing the ends of the wings of the associated spar 9 and the small base of which extends into the space delimited between the two frames of the stacker.

The end plates 10 of each carriage support, near their small base, a horizontal shaft 12 extending parallel to the transport path. This shaft, which serves as a support for two angles 13 each comprising a lifting wing 14 and an immobilization cleat 15, can pivot in the plates 10 and allow the angles to pivot between an active position (visible for example in FIG. 4 ) in which their wing 14 projects horizontally above the transport track while their cleat 15 is in abutment against a retainer 16 fixed on the base of the spar 9, and an inactive position (visible in FIG. 8) in which their wing 14 is outside the transport track while their cleat 15 is below the retainer 16.

Tension springs 17, the ends of which are respectively fixed on the base of the side member 9 and on the wing 14 of the angles are provided to return the latter to their active position.

Referring more particularly to FIG. 10, it will be noted that the shaft 12 extends beyond the end plates 10 and that it carries at each of its ends a radial lug 18 projecting in the direction of the track. transport so as to be able to cooperate with a bypass cam 19 pivotally mounted on the wing of the corresponding upright 6 which is turned towards the transport track.

As can be clearly seen in Figures 5 and 10, the bypass cams 19 are constituted by an L-shaped plate, extending parallel to the upright 6. On its face facing the upright 6, this plate carries an axis 20 by through which it can be pivotally mounted on the upright 6 and a protrusion 21 provided with a bore 22 intended to receive one of the ends of a tension spring 23 the other end of which is hooked on a lug 24 fixed on the upright 6. Thanks to the spring 23, the small branch of the plate is biased against a stop 25 fixed on the external face of the base of the upright 6 and then extends horizontally.

With particular reference to FIG. 10, it will be noted that the axis 20 is fixed at the junction of the two arms of the plate and that a rounded 26 ensures the connection of the outer edges of these two branches.

The bypass cams 19 are fixed on the uprights 6 at a height such that the pins 18 of the shafts 12 meet their large branches when the carriages are in a position close to their low position. The cooperation between the lugs 18 and the bypass cams 19 will however be explained in more detail below during the description of the operation of the stacker and it is therefore not necessary to describe it further here.

To be complete, it will also be specified that each carriage carries on its front plate 10 (the one which is downstream) a stop 27 which is particularly clearly visible in FIGS. 6 to 9. This stop which is perpendicular to the transport track, advances in front of the plate 3 of the product located between the frames of the stacker when the carriages 8 are in their high position (FIG. 6) and descends under the transport track when these move away from their high position (FIGS. 7 to 9) .

Thanks to the stops 27, the product which arrives between the stacker frames, when the carriages are in the high position, can therefore be immobilized in a precise position.

The means making it possible to move the carriages 8 along the uprights 6 will now be described with reference to FIGS. 1 to 4.

As can be seen in these figures, the spar 9 of each carriage rests on two identical cams 28a, 28b extending parallel to the transport track. The cams 28a are fixed to the ends of a transverse shaft 29 resting on bearings 30 mounted on the spacers 7 of the two frames of the stacker. Similarly, the cams 28b are fixed to the ends of another transverse shaft 31 resting on bearings 32 mounted on the spacers 7.

Two parallel levers 33, the upper ends of which are integral with the shaft 29, are articulated on a connecting arm 34 connecting their lower end. They are also articulated at one end of a connecting rod 35 extending parallel to the corresponding spacer 7, the other end of this connecting rod being articulated for its part at the lower end of a lever 36 whose the upper end is wedged on the shaft 31.

The levers 33 and 36 are identical and form the transverse sides of two deformable parallelograms, the longitudinal sides of which are constituted by the connecting rods 35 and the centers of the shafts 29 and 31.

As shown in Figure 4, the link arm 34 is coupled to the rod 37 of a jack 38 whose cylinder 39 is articulated on a base 40 fixed under the transport track. The cylinder 38 extends parallel thereto. When activated, it causes the deformation of the two parallelograms, which forces the cams 28a and 28b to pivot between their extreme positions visible respectively in FIGS. 1 and 3 and in FIG. 2.

It will be noted here that the cams 28a and 28b have a sufficiently long cam surface so that in the high position of the carriages 8, a product can be advanced between the uprights 6 of the frames without risking being hampered by the product which is supported by the lifting wings 14 of the angles 13.

In the example shown, it will also be noted that two tension springs 41 are stretched vertically between the carriages and beams 42 on which the uprights rest 6. Thanks to these springs, the carriages can therefore return more easily to their low position when the cams pivot from their visible position in FIG. 2 to that visible in FIGS. 1 and 3.

The stacker according to the invention also comprises two pusher cleats 43 movable alternately along the side members 1 of the transport track, between a retracted position (visible in FIGS. 1 and 2) in which they are upstream of the two frames and a advanced position (not shown) in which they are downstream of said frames.

These tabs are articulated on slides 44 cooperating with the lower wing of the side members 1 (see in particular FIG. 4), each of these slides being fixed to the rear end (or upstream) of a horizontal rack 45 running along the wall vertical of a beam 1 and whose teeth are engaged with a pinion 46 located downstream of the frames.

It will be noted here that the pinions 46, which are identical, are wedged on a connecting shaft capable of rotating under the control of a conventional motor not shown.

The tabs 43 rise above the plates of the various products on the transport path and are held in their projecting position by a return spring 47 connecting them to their respective slide. This arrangement has the advantage of allowing them to retract either when a plate 3, moving in the direction of the arrow F, passes over them, or when they return to their retracted position while 'a plate 3 is already between the uprights 6.

We will now describe the operation of the stacker according to the invention assuming that the carriages 8 are in their high position visible in FIG. 2 and that the stack of products which is being formed comprises only two products P ₁ and P ₂ superimposed, as shown in Figure 6.

In this position of the carriages 8, the angles 13 are in their active position. In fact, their immobilizing lugs 15 are in abutment against the retainers 16 while their lifting wings 14 extend horizontally and advance under the longitudinal sides of the plate 3 of the lower product P ₂ .

Furthermore, the stops 27 provided at the front end of the carriages 8 project in front of the plate 3 of the product P _{3 which} they immobilized between the uprights 6, the latter having been able to pass freely under the product P ₂ whose height lifting capacity, determined by the length of the surfaces cam cam 28a and 28b is sufficient to allow this passage.

The cylinder 38 is now actuated so that its rod retracts. The latter then pulls the link arm 34 in the direction of the base 40, which causes the deformation of the parallelograms and allows the cams 28a and 28b to pivot in the direction of the arrows G visible in FIG. 2. The carriages therefore initiate their descent with the assistance of the springs 41 which force them to remain in contact with the cam surfaces of the cams 28a and 28b.

When the product P ₂ rests on the product P ₃ , the angles 13 remain in their active position under the action of the springs 17 and this although they are no longer in contact with the plate 3 of the product P ₂ (see the figure 7). Then, while the carriages continue to descend, the lugs 18 of the shafts 12 meet the vertical bypass wing 19 which are immobilized against the stops 25. As the cams 19 cannot be retracted, the lugs 18 constrain the shafts 12 to pivot in the direction of arrow H in FIG. 7. As a result, the angles 13 come into their inactive position shown in FIG. 8 and thus bypass the plate 3 of the product P ₃ without touching it.

As the carriages 8 continue to descend, the pins 18 slide against the vertical wing of the bypass cams 19 while maintaining the angles in their inactive position. Then, when the carriages reach their low position visible in FIGS. 1 and 3, the lugs 18 are located under the bypass cams while the angles return to their active position under the action of the springs 17, their lifting wings 14 being then under the longitudinal sides of the plate of product P ₃ , as shown in FIG. 9.

The cylinder 38 is now actuated in the opposite direction and thus allows the carriages 8 to begin their upward movement. The lugs 18 immediately meet the rounded 26 of the bypass cams 19 and force them to retract against the return force of the springs 23, by pivoting about their axis 20, in the direction of the arrow I (see Figure 10). The cams 19 thus prevent the lugs 18 and the angles 13 from being subjected to an abnormal resistive torque.

While the carriages continue to rise, the bearing wings 14 of the angles then come against the underside of the plate of the product P ₃ , then lift the set of products P _i , P ₂ , P ₃ , this set being raised until the carriages reach their top position again.

A new product can now be advanced along the transport track and brought between the frames of the stacker where the stops 27 of the carriages will ensure its immobilization. The carriages are ready to come down so that their angles can support this new product which will then constitute the lower element of the stack being formed.

The control of the jack 38 and the arrival of the products between the frames can of course be fully automated, which allows the carriages 8 to move continuously between their low and high positions and therefore the stack of products to form without any intervention. manual.

Then, when the stack of products reaches the desired height, the jack 38 ceases to be actuated as soon as the carriages 8 arrive in their low position while the pinion drive motor 46 starts to move in order to move the racks 45 in the direction of arrow F. The tabs 43 then push the stack of products until it is downstream of the stacker frames. When this pushing operation is completed, the pinions 46 are driven in opposite directions in order to bring the cleats 43 back into their retracted position visible in FIGS. 1 and 2.

So the stacker is ready to make a new stack of products.

The triggering of the motor controlling the rotation of the pinions 46 can of course be ensured automatically, for example as a function of signals supplied by limit switches or counting devices adjusted on the number of products which the batteries to be produced must contain.

To be complete, it will be specified that the plates 3 could have no feet. In this case, they would then rest directly on the upper face of the products in the stack which would be located under them.

Claims (9)

1. Stacker for stacking products each formed of a plate (3) supporting an object (5), of the type comprising two frames disposed on each side of a transport path (1, 2) along with the products travel one after the other; means (27) for immobilizing the products when they are between the frames ; two lifting carriages (8) movable vertically along the frames, these carriages facing each other and each comprising lifting means (13) having a lifting arm (14) adapted to advance under the product immobilized between the frames, the lifting means (13) being hingedly mounted about a horizontal shaft (12) extending parallel to the transport path (1, 2) and being adapted for pivoting between an active position in which they are in abutment against a stop (16) fixed on the corresponding carriage (8) while their lifting arm (14) advances horizontally above the transport path (1, 2) and an inactive position in which they are distant from the stop (16) whereas their lifting arm (14) extends outside the transport path (1, 2) ; and drive means for communicating cyclically to the carriagesa rising movement during which their lifting means raise the immobilized product to a height sufficient to allow a new product to arrive and stop between the frames, then a downward movement during which their lifting means deposit the raised product on the new product and then come underneath this latter, characterized in that the pivoting shaft (12) of the lifting means (13) of the same carriage (8) is provided with a radial stud (18) adapted for cooperation with a by-pass cam (19) mounted for pivoting on the corresponding frame, about an axis (20) perpendicular to the pivoting shaft (12) of the lifting means ; and in that the by-pass cam (19) is urged resiliently against a stop (25) provided on said corresponding frame, the stop (25) being disposed so that, during the downward movement of the corresponding carriage (8), the corresponding stud (18) causes the lifting means (13) to move into their inactive position when it meets the by-pass cam (19) which is immobilized against the stop (25), and that during the upward movement of the corresponding carriages (8) the associated stud (18) causes the by-pass cam (19) to pivot about the axis (20) so as to move it away from the stop (25) and to retract it.

2. Stacker according to claim 1, characterized in that the drive means are formed by two identical sets of cams (28a, 28b), on which the carriages (8) rest, each set bearing on a horizontal strut (7) provided on the corresponding frame and comprising two cams (28a, 28b) each fixed on a lever (33 respectively 36) forming one of the transverse sides of a deformable parallelogram, and by an actuating cylinder (38) extending parallel to the transport path (1, 2), this cylinder being inserted between a fixed base (40) and a connecting arm (34) connecting the two deformable parallelograms together.

3. Stacker according to claim 2, characterized in that the connecting arm (34) extends between the free arms of the two facing levers (33 respectively 36).

4. Stacker according to claim 2, characterized in that the drive means raise the carriages (8) against the action exerted by traction springs (41) inserted between these latter and the lower part of the frames.

5. Stacker according to any of the preceding claims, characterized in that it further comprises means (43) for pushing the pile of products when it reaches a predetermined height, these means bringing the pile downstream of the frames while moving it along the transport path (1, 2).

6. Stacker according to claim 5, characterized in that the means for pushing the pile comprise at least one lug (43) reciprocally movable along the part of the transport path (1, 2) situated between the frames, this lug rising above the plate (3) of the product resting on the transport path and being retractable when it moves in the direction in which it does not exert its pushing action.

7. Stacker according to claim 6, characterized in that the lug (43) is hingedly mounted to one of the ends of a rack (45) extending along the transport path (1, 2) and movable parallel thereto under the action of a drive means (46) engaged therewith.

8. Stacker according to any one of the preceding claims, further characterized in that the means for immobilizing the products between the frames are formed by stops (27) fixed at the front end of each carriage (8) ; these stops being in front of the plate (3) of the product to be immobilized when the carriages are in their high position and under the transport path (1, 2) when these latter are in their low position. 9. Stacker according to claim 9, characterized in that the two frames thereof each comprise two vertical uprights (6) formed by channel sections whose flanges are parallel to each other and face each other, and in that the carriages are each formed by a horizontal side member (9) whose ends bear rollers (11) cooperating with the flanges of the vertical uprights (6) of the corresponding frame.

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